As a prelude to physiological experiments, the ultrastructure of bentic foraminifera inhabiting the REDOX discontinuity layer of marine sediments in the Santa Barbara Basin are being investigated for possible clues concerning their adaptations to such a geochemical environment. To date, we have found what appear to be magnetotactic bacteria in one foraminiferal species, and cyanobacterial symbionts in another. Neither of these observations have previously been reported in the literature. By viewing thick preparations in stereo on the HVEM we hope to gain more knowledge of the bacteria as well as other ultrastructural features of the forams such as peroxisome-E.R. complexes. These latter structures are lost during routine thin but not thick sectioning.